CN108884193B

CN108884193B - Ethylene/alpha-olefin copolymer having excellent environmental stress cracking resistance

Info

Publication number: CN108884193B
Application number: CN201780021146.6A
Authority: CN
Inventors: 宣淳浩; 裵要韩; 李亨一; 崔二永; 洪福基; 李承珉; 金善美; 朴珍映
Original assignee: LG Chem Ltd
Current assignee: LG Chem Ltd
Priority date: 2016-11-15
Filing date: 2017-11-02
Publication date: 2024-05-07
Anticipated expiration: 2037-11-02
Also published as: KR102090811B1; EP3415540A1; EP3415540B1; KR20180054443A; EP3415540A4; WO2018093078A8; US10815324B2; CN108884193A; WO2018093078A1; US20200048381A1

Abstract

An ethylene/alpha-olefin copolymer having excellent environmental stress cracking resistance is provided.

Description

Ethylene/alpha-olefin copolymer having excellent environmental stress cracking resistance

Technical Field

Cross Reference to Related Applications

The present application is based on and claims priority from korean patent application No. 10-2016-0152221 filed on the date 2016, 11 and 15, the disclosure of which is hereby incorporated by reference in its entirety.

The present invention relates to an ethylene/α -olefin copolymer having excellent crack resistance.

Background

For resins used as food containers and the like, excellent processability, mechanical properties and environmental stress cracking resistance are required. Accordingly, there is a continuing need for a technique for preparing polyolefins that meet the requirements of high molecular weight, broader molecular weight distribution, and preferred comonomer distribution, etc., for preferred application to containers, bottle caps, etc.

Meanwhile, the use of a group 4 transition metal metallocene catalyst can easily control the molecular weight and molecular weight distribution of polyolefin and can control the comonomer distribution of polymer, compared to the existing ziegler-natta catalyst, and thus, has been used for preparing polyolefin having both improved mechanical properties and processability. However, the polyolefin prepared using the metallocene catalyst has a problem in terms of lower processability due to a narrow molecular weight distribution.

In general, as the molecular weight distribution becomes wider, the decrease in viscosity according to the shear rate becomes larger, and thus excellent workability is exhibited in the processing region. However, the polyolefin prepared using the metallocene catalyst has a high viscosity at a high shear rate due to a relatively narrow molecular weight distribution, and thus a high load or pressure is applied thereto at the time of extrusion. As a result, there are disadvantages in that extrusion productivity is lowered, bubble stability is significantly lowered during the blow molding process, and the molded article produced has surface unevenness, resulting in lowered transparency, and the like.

Thus, a multistage reactor comprising a plurality of reactors has been employed to obtain a polyolefin having a broad molecular weight distribution using a metallocene catalyst, and attempts have been made to obtain a polyolefin satisfying both a broader multimodal molecular weight distribution and a high molecular weight through respective polymerization steps in the plurality of reactors.

However, due to the high reactivity of the metallocene catalyst, it is difficult to properly polymerize polyolefin in the reactor of the latter stage due to the duration of polymerization in the reactor of the former stage, and as a result, there is a limit in the preparation of polyolefin satisfying both a sufficiently high molecular weight and a wider multimodal molecular weight distribution. Thus, there is a continuing need to develop techniques that can more efficiently produce polyolefins that can have high molecular weights and broader multimodal molecular weight distributions to meet both mechanical properties and processability, and can be preferred for use in products.

U.S. Pat. No. 6,180,736 describes a process for preparing polyethylene using a metallocene catalyst in a single gas phase reactor or a continuous slurry reactor. With this method, there are advantages in that the polyethylene production cost is low, scaling hardly occurs, and the polymerization activity is stable. In addition, U.S. patent No. 6,911,508 describes the preparation of polyethylene with improved rheological properties by using novel metallocene catalyst compounds using 1-hexene as comonomer in a single gas phase reactor. However, the polyethylenes described in these patents also have a narrow molecular weight distribution, and thus it is difficult to obtain sufficient impact strength and processability.

U.S. patent 4,935,474 describes a process for preparing polyethylene having a broad molecular weight distribution using two or more metallocene compounds. In addition, U.S. patent No. 6,841,631 and U.S. patent No. 6,894,128 describe the use of metallocene-based catalysts having at least two metal compounds to prepare polyethylenes having bimodal or multimodal molecular weight distribution, and which can be used in the preparation of films, pipes, hollow shaped articles, and the like. However, although the prepared polyethylene has improved processability, there is still a problem in that the dispersion state per molecular weight in unit particles is not uniform, and thus the appearance is rough and the physical properties are unstable even under relatively favorable processing conditions.

In this context, there is a continuous need for the preparation of an excellent resin having a balance between physical properties or a balance between physical properties and processability, and further studies thereof are required.

Disclosure of Invention

[ Technical problem ]

In order to solve the problems of the prior art, the present invention provides an ethylene/α -olefin copolymer having excellent environmental stress cracking resistance.

Technical scheme

In order to achieve the above object, the present invention provides an ethylene/α -olefin copolymer which satisfies the following conditions:

a weight average molecular weight of 50,000g/mol to 250,000g/mol,

Molecular weight distribution (Mw/Mn) of 4 to 20,

A density of 0.950g/cm ³ to 0.965g/cm ³,

A melt flow rate ratio (MFR ₅/MFR_2.16, measured at 190 ℃ according to ASTM 1238) of 3 to 10, and

Environmental stress crack resistance (measured according to ASTM D1693-B) of greater than 150 hours.

Environmental Stress Crack Resistance (ESCR) is considered to be one of the very important properties of resins for food containers, bottle caps, etc. ESCR is an index for determining the stability and tolerance of a resin to oils and fats contained in foods and the like, and is important for ensuring the continuous performance of the resin.

High molecular weight polymers are generally known to have improved mechanical properties compared to low molecular weight polymers, and thus environmental stress crack resistance may be improved as the molecular weight of the polymer increases. However, as the molecular weight increases, there is a problem in that the processability and flowability decrease.

However, the ethylene/α -olefin copolymer according to the present invention may have a high molecular weight distribution and a high melt flow rate ratio while having improved environmental stress cracking resistance, and thus, the ethylene/α -olefin copolymer has excellent processability, which is advantageous in its molding. Therefore, it can be applied to various fields.

The ethylene/alpha-olefin copolymer according to the invention has a weight average molecular weight of 50,000g/mol to

250,000G/mol. The weight average molecular weight is preferably 100,000 or more, 110,000 or more, 120,000 or more, 130,000 or more, 140,000 or more, 150,000 or more, 160,000 or more, 170,000 or more, or 180,000 or more. Further, the weight average molecular weight is preferably 240,000 or less, 230,000 or less, or 220,000 or less.

The ethylene/alpha-olefin copolymer according to the present invention has a molecular weight distribution (Mw/Mn) of 4 to 20. The molecular weight distribution is preferably 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more. The molecular weight distribution is preferably 19 or less, 18 or less, 17 or less, 16 or less, or 15 or less.

The ethylene/alpha-olefin copolymer according to the invention has a melt flow rate ratio (MFR ₅/MFR_2.16, measured at 190 ℃ according to ASTM 1238) of 3 to 10. The melt flow rate ratio is preferably 4 or more or 5 or more. Further, the melt flow rate ratio is preferably 9 or less or 8 or less.

Furthermore, the ethylene/α -olefin copolymer according to the present invention has an Environmental Stress Crack Resistance (ESCR) of 150 hours or more, and more preferably 200 hours or more, measured according to ASTM D1693-B. If the Environmental Stress Crack Resistance (ESCR) is 150 hours or more, the copolymer can stably maintain performance when used as a food container or the like. Therefore, the upper limit is not substantially important. However, for example, the upper limit may be about 1,000 hours or less, 900 hours or less, 800 hours or less, 700 hours or less, 500 hours or less, or 400 hours or less. As such, since the ethylene/α -olefin copolymer exhibits high performance against environmental stress cracking, it has high stability when molded into a product, and can maintain continuous performance.

Further, the ethylene/α -olefin copolymer according to the present invention has a crack resistance of 100 hours or more, measured according to the following method.

-Applying a water pressure of 5 bar to the inside of the cap, while immersing the cap obtained by injection moulding of the ethylene/α -olefin copolymer (28 mm cap according to PET standard PCO 1881) in a bath containing 5% igepal solution, and measuring the time at which the water pressure starts to drop.

In addition, the ethylene/alpha-olefin copolymer may comprise an ethylene homopolymer or may comprise other comonomers in addition to ethylene. The comonomer content is preferably 0.5 to 5 wt.%, relative to the metallocene polypropylene. The comonomer may be an alpha-olefin having 3 to 10 carbon atoms other than ethylene, for example, the comonomer may include one or more selected from the group consisting of 1-propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene (1-docene), 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene (1-eicosens), and mixtures thereof. Preferably, the comonomer may be 1-butene.

The ethylene/α -olefin copolymer may be prepared by polymerizing a metallocene compound comprising the following chemical formula 1; a first cocatalyst compound; a borate-based second promoter; and a carrier prepared by polymerizing ethylene and the comonomer in the presence of a catalyst supporting a single metallocene compound:

[ chemical formula 1]

(Cp¹R¹)_n(Cp²R²)MX_3-n

In the chemical formula 1, the chemical formula is shown in the drawing,

M is a group 4 transition metal;

Cp ¹ and Cp ² are the same or different from each other and are each independently any one selected from the group consisting of cyclopentadienyl, indenyl, 4,5,6, 7-tetrahydro-1-indenyl, and fluorenyl, which groups may be substituted with hydrocarbons having 1 to 20 carbon atoms, provided that neither Cp ¹ nor Cp ² is a cyclopentadienyl group;

R ¹ and R ² are identical to or different from each other and are each independently hydrogen, C1 to C20 alkyl, C1 to C10 alkoxy, C2 to C20 alkoxyalkyl, C6 to C20 aryl, C6 to C10 aryloxy, C2 to C20 alkenyl, C7 to C40 alkylaryl, C7 to C40 arylalkyl, C8 to C40 arylalkenyl or C2 to C10 alkynyl;

X is a halogen atom, a C1 to C20 alkyl group, a C2 to C10 alkenyl group, a C7 to C40 alkylaryl group, a C7 to C40 arylalkyl group, a C6 to C20 aryl group, a substituted or unsubstituted C1 to C20 alkylene group, a substituted or unsubstituted amino group, a C2 to C20 alkylalkoxy group, or a C7 to C40 arylalkoxy group; and

N is 1 or 0.

The method of preparing the single metallocene compound-supported catalyst includes supporting the metallocene compound of chemical formula 1 on a support before or after supporting the first cocatalyst (e.g., an organometallic compound including aluminum) on the support.

In the single metallocene supported catalyst, the molar ratio of metal contained in the metallocene compound to boron contained in the borate-based second cocatalyst may be from about 1:0.5 to about 1:3, or from about 1:0.8 to about 1:2, or from about 1:0.9 to about 1:1.5. If the molar ratio is less than 1:0.5, there is a problem in that the catalytic activity may be lowered, whereas if it is more than 1:3, although the activity is excellent, there is a disadvantage in that the polymerization reactivity is not uniform and thus the process operation is not easy.

In addition, in the single metallocene-supported catalyst, examples of specific substituents of chemical formula 1 are as follows.

The C1 to C20 alkyl group may include a linear or branched alkyl group, and specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and the like.

The C2 to C20 alkenyl group may include a straight chain or branched alkenyl group, and specifically, an allyl group, a vinyl group, a propenyl group, a butenyl group, a pentenyl group, and the like.

The C6 to C20 aryl group may include a monocyclic or polycyclic aryl group, and specifically, phenyl, biphenyl, naphthyl, phenanthryl, fluorenyl, and the like.

The C1 to C10 alkoxy groups may include methoxy, ethoxy, phenoxy, hexyloxy, and the like.

The C2 to C20 alkoxyalkyl group may include a methoxymethyl group, a t-butoxymethyl group, a t-butoxyhexyl group, a 1-ethoxyethyl group, a 1-methyl-1-methoxyethyl group, and the like.

The group 4 transition metal may include titanium, zirconium, hafnium, and the like.

The metallocene compound represented by chemical formula 1 may be, for example, a compound represented by any one of the following structural formulas, but is not limited thereto:

In the single metallocene compound-supported catalyst, the support for supporting the metallocene compound may contain hydroxyl groups on the surface thereof. That is, the smaller the content of hydroxyl groups (-OH) on the surface of the carrier, the better, but it is practically difficult to remove all the hydroxyl groups. Therefore, the content of the hydroxyl group can be controlled by the preparation method and conditions of the carrier, or drying conditions (temperature, time, drying method, etc.), and the like. For example, it is preferable that the content of hydroxyl groups on the surface of the support is 0.1mmol/g to 10mmol/g, more preferably 0.5mmol/g to 1mmol/g. If the content of the hydroxyl groups is less than 0.1mmol/g, the sites for reaction with the cocatalyst may be reduced, whereas if it is more than 10mmol/g, there is a possibility that the hydroxyl groups may come from moisture other than the hydroxyl groups present on the surface of the support, which is not preferable.

In this regard, in order to reduce side reactions due to a small amount of hydroxyl groups remaining after drying, a carrier in which hydroxyl groups are chemically removed while preserving highly reactive siloxane groups participating in the loading may be employed.

In this case, it is preferable that the support has highly reactive hydroxyl groups and siloxane groups on its surface. Examples of the carrier may include high temperature dried silica, silica-alumina or silica-magnesia, etc., which may generally contain an oxide, carbonate, sulfate or nitrate component, such as Na ₂O、K₂CO₃、BaSO₄ or Mg (NO ₃)₂, etc.

The support is preferably substantially dried prior to loading the first and second cocatalysts. In this regard, the drying temperature of the support is preferably 200 ℃ to 800 ℃, more preferably 300 ℃ to 600 ℃, and most preferably 400 ℃ to 600 ℃. If the drying temperature of the support is lower than 200 ℃, moisture on the surface may react with the cocatalyst due to excessive moisture, whereas if the drying temperature is higher than 800 ℃, pores on the surface of the support may merge to reduce the surface area, and a large number of hydroxyl groups on the surface may disappear and only siloxane groups may remain, thereby reducing the reaction sites with the cocatalyst, which is not preferable.

At the same time, the single metallocene catalyst may comprise a first cocatalyst and a second cocatalyst in order to produce an active catalyst species. By using these two cocatalysts, the catalytic activity can be improved, and in particular, by using the second cocatalyst, the molecular weight distribution of the polyolefin can be controlled.

The first cocatalyst may be any cocatalyst as long as it is used when polymerizing olefins in the presence of a general metallocene catalyst. By means of the first cocatalyst, a bond between the hydroxyl group in the support and the group 13 transition metal is formed. Furthermore, the first cocatalyst can help to ensure the unique performance of the single metallocene supported catalyst of the present invention, as the first cocatalyst is only present on the surface of the support to avoid fouling (where polymer particles coagulate to the wall surfaces of the reactor or to each other).

In the single metallocene compound-supported catalyst, the first cocatalyst may be one or more selected from the compounds represented by the following chemical formulas 2 and 3:

[ chemical formula 2]

-[Al(R³)-O]_a-

[ Chemical formula 3]

D(R⁴)₃

In the chemical formulas 2 and 3,

R ³ may be the same as or different from each other and are each independently halogen or a C1 to C20 hydrocarbon group substituted or unsubstituted with halogen, and a is an integer of 2 or more,

R ⁴ may be the same as or different from each other and are each independently halogen; a C1 to C20 hydrocarbon, or a C1 to C20 hydrocarbon substituted with halogen, and

D is aluminum or boron.

Examples of the compound represented by chemical formula 2 may include methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, etc. and a more preferred compound is methylaluminoxane.

Examples of the compound represented by chemical formula 3 may include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, triisopropylaluminum, tri-sec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylmethoxyaluminum, dimethylethoxyaluminum, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, and the like, and more preferable compounds may be selected from trimethylaluminum, triethylaluminum, and triisobutylaluminum.

Meanwhile, the second borate-based cocatalyst included in the single metallocene compound catalyst described in the present invention may be a borate-based compound represented by the following chemical formula 4 or 5:

[ chemical formula 4]

[L-H]⁺[Z(A)₄]^-

[ Chemical formula 5]

[L]⁺[Z(A)₄]^-

In the chemical formulas 4 and 5,

L is each independently a neutral or cationic lewis acid, H is each independently a hydrogen atom, Z is each independently boron, and a is each independently a halogen of 1 or more hydrogen valence, a C1 to C20 hydrocarbon group (hydrocaryl group), an alkoxy group, a phenoxy group, a C6 to C20 aryl group, or an alkyl group substituted with a nitrogen, phosphorus, sulfur, or oxygen atom.

It may be preferred that the borate-based second promoter comprises trityl tetrakis (pentafluorophenyl) borate, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, trimethylammonium tetrakis (pentafluorophenyl) borate, triethylammonium tetrakis (pentafluorophenyl) borate or tripropylammonium tetrakis (pentafluorophenyl) borate. The cocatalysts of the present invention are useful in preparing polyolefins suitable for fiber preparation and thus exhibit specificity for use and preparation process.

Meanwhile, when preparing the single metallocene catalyst, the order of loading the respective components preferably includes the steps of: as described above, the metallocene compound of chemical formula 1 is supported before or after the first cocatalyst is supported on the carrier; and supporting the borate-based second promoter on the support.

Further, the load condition is not particularly limited, and the load may be performed within a range known to those skilled in the art. For example, the loading may be performed by appropriately using a high temperature load and a low temperature load, and in particular, the loading of the first cocatalyst and the second cocatalyst may be performed at a temperature of about 25 ℃ to about 100 ℃. In this regard, the loading time of the first cocatalyst and the loading time of the second cocatalyst may be appropriately controlled according to the amount of cocatalysts to be loaded. In addition, the temperature at which the metallocene compound reacts with the support may be from about-30 ℃ to about 150 ℃, preferably from room temperature to about 100 ℃, and more preferably from about 30 ℃ to about 80 ℃. The supported catalyst which has reacted may be used as it is after the reaction solvent is removed by filtration or vacuum distillation, and if necessary, it may be used after Soxhlet filtration with aromatic hydrocarbon such as toluene.

Furthermore, during the polymerization, the metallocene-supported catalyst may be diluted with a C5 to C12 aliphatic hydrocarbon-containing solvent such as isobutene, pentane, hexane, heptane, nonane, decane and isomers thereof; aromatic hydrocarbon solvents such as toluene and benzene; the hydrocarbon solvent substituted with chlorine atoms, such as methylene chloride and chlorobenzene, etc. The solvent is preferably treated with a small amount of aluminum to remove small amounts of water, air, etc., which act as catalyst poisons prior to use.

The polymerization may be performed by a standard method while continuously supplying the olefin monomer in a predetermined ratio using only one reactor selected from the group consisting of a continuous slurry polymerization reactor, a loop slurry reactor, a gas phase reactor and a solution reactor, or using two or more identical or different reactors.

During the polymerization, the polymerization temperature is preferably from about 25 ℃ to about 500 ℃, more preferably from about 25 ℃ to about 200 ℃, and even more preferably from about 50 ℃ to about 150 ℃. Further, the polymerization pressure is preferably from about 1Kgf/cm ² to about 100Kgf/cm ², more preferably from about 1Kgf/cm ² to about 70Kgf/cm ², and most preferably from about 5Kgf/cm ² to about 50Kgf/cm ².

[ Advantageous effects ]

As described above, the ethylene/α -olefin copolymer according to the present invention is characterized by having excellent environmental stress cracking resistance.

Detailed Description

Hereinafter, preferred embodiments will be provided to better understand the present invention. However, the following examples are provided only for easier understanding of the present invention, but the contents of the present invention are not limited thereto.

Preparation example

To a well dried 250mL Schlenk bottle was added 11.6mL (100 mmol) of indene diluted in 80mL of THF followed by stirring. 48mL of a 2.5M nBuLi hexane solution was slowly added thereto, and after 3 hours, 18.3g (95 mmol) of 6-chlorohexyl tert-butyl ether was added and reacted for about 12 hours. It was observed that as the reaction proceeded, the reaction mixture became a pale pink suspension. After the reaction was completed, 100mL of water was added to the mixture, followed by extraction with 100mL of diethyl ether three more times. The collected organic layer was dried over MgSO ₄, after which the solvent was removed by vacuum filtration and additional vacuum distillation at 100℃and 20mmHg, to give pure tether-indene ligand in 90% yield.

¹H NMR(500MHz,CDCl₃)：1.22(9H,s),1.62(2H,m),1.77(2H,m),2.58(2H,m),3.36(2H,s),3.42(2H,m),6.28(1H,s),7.19(1H,m),7.24(1H,m),7.40(1H,m),7.48(1H,m)

10Mmol of the obtained ligand was dissolved in 45mL of diethyl ether, and 5mL (1.25 eq.) of nBuLi in hexane was added thereto. After 6 hours, 20g (0.95 eq.) of nBuCpZrCl ₃ toluene solution (0.273 g/mmol) was slowly added thereto at-78℃and the temperature was raised and the solution was stirred for an additional 1 day. The reaction mixture was passed through a filter to obtain a filtrate, which was concentrated, extracted with 100mL of hexane, and concentrated again to obtain the title compound in a yield of 90% or more.

¹H NMR(500MHz,CDCl₃)：0.93(3H,t),1.15(9H,s),1.24～1.55(10H,m),1.58～1.64(2H,m),3.34(2H,m),5.77(0.5H,s),5.82(1H,m),6.02(0.5H,s),6.40(1H,s),6.62(1H,s),7.26(2H,m),7.42(2H,m)

Example 1

Step 1) preparation of Supported catalyst

49.7ML of a 10wt% Methylaluminoxane (MAO)/toluene solution was charged into a glass reactor, 9.1g of silica (product name: grace 952, particle size: 30 μm, surface area: 300m ²/g, pore volume: 1.6mL/g, pore diameter: 20 nm) was added at 40℃and then the solution was stirred at 200rpm for 16 hours while raising the temperature of the reactor to 60 ℃. Thereafter, the temperature was again lowered to 40℃and 441mg of the metallocene compound of the production example was dissolved in toluene in the form of a solution and introduced, followed by stirring for 2 hours. Next, 730mg of N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate was dissolved in 20mL of toluene and introduced as a solution, followed by stirring at 40℃for 2 hours. After the completion of the reaction, stirring was stopped, the toluene layer was separated and removed, and then residual toluene was removed under reduced pressure at 40℃to prepare a catalyst loaded with a single metallocene.

Step 2) preparation of ethylene/1-butene copolymer

The polymerization is carried out by adopting the prepared supported catalyst and hexane slurry stirred tank process. The polymerization conditions included 10kg/hr of ethylene, 7kg/cm ² of pressure, 82℃of temperature, 3g/hr of hydrogen and 7cc/min of 1-butene.

Example 2

An ethylene/1-butene copolymer was produced in the same manner as in example 1 except that the polymerization conditions of 3.5g/hr of hydrogen were employed in step 2 of example 1.

Example 3

An ethylene/1-butene copolymer was produced in the same manner as in example 1 except that the polymerization conditions of 3.6g/hr of hydrogen were employed in step 2 of example 1.

Example 4

An ethylene/1-butene copolymer was produced in the same manner as in example 1 except that the polymerization conditions of 3.7g/hr of hydrogen were employed in step 2 of example 1.

Example 5

An ethylene/1-butene copolymer was produced in the same manner as in example 1 except that the polymerization conditions of 3.3g/hr of hydrogen were employed in step 2 of example 1.

Comparative examples 1 to 4

The following compounds were used as comparative examples.

Comparative example 1: CAP602 (InEOS)

Comparative example 2: CAP508 (Yinglioshi Co.)

Comparative example 3: h ME1000 (LG chemical Co., ltd.)

Comparative example 4: m5220 (daol (Total)) company

Experimental examples

The physical properties of the copolymers of examples and comparative examples were evaluated by the following methods.

1) Density: ASTM D1505.

2) Melt index (MFR, 5kg/2.16 kg): measured temperature at 190 ℃, ASTM 1238.

3) MFRR (MFR ₅/MFR_2.16)：MFR₅ melt index (MI, load of 5 kg)) divided by MFR _2.16 (MI, load of 2.16 kg).

4) Mn, M _w and MWD: the samples were pretreated for 10 hours by dissolving in 1,2, 4-trichlorobenzene containing 0.0125% BHT at 160℃using PL-SP260, and the number average molecular weight and weight average molecular weight were measured using PL-GPC220 at a measurement temperature of 160 ℃. The molecular weight distribution is represented by the ratio of the weight average molecular weight to the number average molecular weight.

5) Environmental Stress Cracking Resistance (ESCR): the time to F50 (50% destruction) was measured according to ASTM D1693-B using 10% Igepal CO-630 solution at a temperature of 50 ℃.

6) Crack resistance: the ethylene/alpha-olefin copolymer and a 120 ton screw were used at a processing temperature of 240 ℃, an injection rate of 78mm/s and a holding pressure of 650 barStandard Angel injection molding machine to make caps (28 mm caps according to PET standard PCO 1881). While immersing the molded cap in a bath containing 5% igepal solution, a water pressure of 5 bar was applied to the inside of the cap, and the time at which the water pressure began to drop was measured.

The results are shown in table 1 below.

TABLE 1

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Claims

1. An ethylene/1-butene copolymer wherein

A weight average molecular weight of 180,000g/mol to 220,000g/mol,

The molecular weight distribution Mw/Mn is from 4 to 20,

A density of 0.950g/cm ³ to 0.965g/cm ³,

A melt flow rate ratio MFR ₅/MFR_2.16 to 10, measured at 190 ℃ according to ASTM 1238, and

An environmental stress crack resistance of 150 hours or more, said environmental stress crack resistance measured according to ASTM D1693-B,

The crack resistance is 100 hours or more, the crack resistance is that water pressure of 5 bar is applied to the inside of a cap obtained by injection molding of the ethylene/1-butene copolymer, and when the cap is immersed in a bath containing 5% igepal solution, the water pressure starts to drop, the cap is a 28mm cap according to PET standard PCO 1881,

Wherein the ethylene/1-butene copolymer is composed of a metallocene compound of the following chemical formula 1; a first cocatalyst compound; a borate-based second promoter; and the preparation of a single metallocene compound-supported catalyst in the presence of a carrier:

[ chemical formula 1]

(Cp¹R¹)_n(Cp²R²)MX_3-n

In the chemical formula 1, the chemical formula is shown in the drawing,

M is a group 4 transition metal;

Cp ¹ and Cp ² are the same or different from each other and are each independently any one selected from cyclopentadienyl, indenyl, 4,5,6, 7-tetrahydro-1-indenyl and fluorenyl, these groups being optionally substituted by hydrocarbons having from 1 to 20 carbon atoms, provided that all Cp ¹ and Cp ² are not cyclopentadienyl;

x is a halogen atom, a C1 to C20 alkyl group, a C2 to C10 alkenyl group, a C7 to C40 alkylaryl group, a C7 to C40 arylalkyl group, a C6 to C20 aryl group, a substituted or unsubstituted amino group, a C2 to C20 alkylalkoxy group, or a C7 to C40 arylalkoxy group; and

N is 1 or 0.

2. The ethylene/1-butene copolymer according to claim 1 wherein

The molecular weight distribution Mw/Mn is from 10 to 15.

3. The ethylene/1-butene copolymer according to claim 1 wherein

The melt flow rate ratio is from 5 to 8.

4. The ethylene/1-butene copolymer according to claim 1 wherein

The environmental stress crack resistance is from 200 hours to 400 hours.